Researchers from University College London (UCL) analyzed data from more than 10,000 children born in 2000 to 2002 who were enrolled in the U.K. Millennium Cohort Study. The investigative team collected bedtime information when the children were 3-, 5- and 7-years-old, as well as reports from the children’s mothers and teachers about behavioral issues, such as hyperactivity, conduct problems, problems with peers and emotional difficulties. Children with attention-deficit/hyperactivity disorder (ADHD) and an autism spectrum disorder were not included in the investigation.
The study found that kids with irregular bedtimes had more behavioral problems than did children who went to sleep at regular hours. Researchers also found that the longer a child was allowed to go to bed at different hours each night the worse the reported behavior problems.
“What we’ve shown is that these effects build up incrementally over childhood, so that children who always had irregular bedtimes were worse off than those children who did have a regular bedtime at one or two of the ages when they were surveyed,” study co-author Yvonne Kelly, PhD, a professor in the research department of epidemiology and public health, University College of London, said in a UCL news release.
Kelly explained how irregular bedtimes could affect behavior: “First, switching bedtimes from night to night interferes with circadian rhythms [a person’s body clock] and induces a state akin to jet lag. Second, disrupted sleep interferes with processes to do with brain maturation,” she told HealthDay.
There is good news from the study, however. Children who were switched from an irregular bedtime schedule to one that was consistent, showed an improvement in behavior.
“Getting regular routines around bedtime appears to be important for children’s behavioral development,” concluded Kelly.
But she also acknowledged that a consistent schedule is not always possible.
“There are lots of other influential factors, too. So we shouldn’t get too hung up about children having the same bedtime every single night,” she added.